This invention relates to a passive vehicle occupant restraint belt system in which the belt is automatically, easily and effectively transferred between an occupant-restraining position and an occupant-releasing position in response to opening and closing movements of a door, and more particularly, to a system wherein the motion amplifying mechanism thereof is greatly simplified.
In many conventional passive restraint belt systems, the belt is transferred between the restraining position and the releasing position by a mechanical drive system including an amplifier mechanism and a lever responsive to the opening and closing of the door installed on the door between the hinged end of the door and the vehicle body. Because the displacement of the door at the hinged end is relatively small, the movement of the lever must be multiplied considerably to move the belt hanger along the guide rail between the restraining and releasing positions. The multiplication factor is often above 5 and may range higher than 20.
Various proposals have been offered to reduce this multiplication factor, as for example, an amplifier arrangement comprising several pairs of pulleys connected by crossed-cords. However, this pulley-type arrangement adds considerably to the force required to open and close the door, and therefore is not especially practical. Other systems have been proposed which operate to move the belt fully from the restraining position to the releasing position only during the initial opening movement of the door. These arrangements typically also require a strong manual force, however.